Ataxia-telangiectasia: A review of clinical features and molecular pathology

Pioglitazone as a Possible Treatment for Ataxia-Telangiectasia

Ataxia-telangiectasia (AT) is a rare autosomal recessive disorder characterized by immunodeficiency, progressive cerebellar ataxia, and an increased malignancy risk. Cells derived from individuals with AT show multiple defects, including high oxidant and ionizing radiation sensitivities, poor DNA repair, low iron-sulfur cluster levels, and low reduced glutathione. The clinical course of AT is progressive and unrelenting, with most individuals having a survival time of approximately twenty-five years. Presently, AT has no effective treatments, and most patients receive supportive care only. Recently, pioglitazone, a thiazolidinedione class used to treat type 2 diabetes, has been demonstrated to exert beneficial effects on AT cells and on diabetic individuals with AT. Here, I will discuss the possible molecular mechanisms of pioglitazone's favorable effects on the AT phenotype and why it may have utility in treating some aspects of AT.

CHARON: An Imaging-Based Diagnostic Algorithm to Navigate Through the Sea of Hereditary Degenerative Ataxias

The complexity in diagnosing hereditary degenerative ataxias lies not only in their rarity, but also in the variety of different genetic conditions that can determine sometimes similar and overlapping clinical findings. In this light, Magnetic Resonance Imaging (MRI) plays a key role in the evaluation of these conditions, being a fundamental diagnostic tool needed not only to exclude other causes determining the observed clinical phenotype, but also to proper guide to an adequate genetic testing. Here, we propose an MRI-based diagnostic algorithm named CHARON (Characterization of Hereditary Ataxias Relying On Neuroimaging), to help in disentangling among the numerous, and apparently very similar, hereditary degenerative ataxias. Being conceived from a neuroradiological standpoint, it is based primarily on an accurate evaluation of the observed MRI findings, with the first and most important being the pattern of cerebellar atrophy. Along with the evaluation of the presence, or absence, of additional signal changes and/or supratentorial involvement, CHARON allows for the identification of a small groups of ataxias sharing similar imaging features. The integration of additional MRI findings, demographic, clinical and laboratory data allow then for the identification of typical, and in some cases pathognomonic, phenotypes of hereditary ataxias.

Clinical and genetic spectrum of Ataxia Telangiectasia Tunisian patients: Bioinformatic analysis unveil mechanisms of ATM variants pathogenicity

Ataxia Telangiectasia (AT) is a rare multisystemic neurodegenerative disease caused by biallelic mutations in the ATM gene. Few clinical studies on AT disease have been conducted in Tunisia, however, the mutational landscape is still undefined. Our aim is to determine the clinical and genetic spectrum of AT Tunisian patients and to explore the potential underlying mechanism of variant pathogenicity. Sanger sequencing was performed for nine AT patients. A comprehensive computational analysis was conducted to evaluate the possible pathogenic effect of ATM identified variants. Genetic screening of ATM gene has identified nine different variants from which six have not been previously reported. In silico analysis has predicted a pathogenic effect of identified mutations. This was corroborated by a structural bioinformatics study based on molecular modeling and docking for novel missense mutations. Our findings suggest a profound impact of identified mutations not only on the ATM protein stability, but also on the ATM-ligand interactions. Our study characterizes the mutational landscape of AT Tunisian patients which will allow to set up genetic counseling and prenatal diagnosis for families at risk and expand the spectrum of ATM variants worldwide. Furthermore, understanding the mechanism that underpin variant pathogenicity could provide further insights into disease pathogenesis.

ATM germ line pathogenic variants affect outcomes in children with ataxia-telangiectasia and hematological malignancies

ABSTRACT

Ataxia-telangiectasia (A-T) is an autosomal-recessive disorder caused by pathogenic variants (PVs) of the ATM gene, predisposing children to hematological malignancies. We investigated their characteristics and outcomes to generate data-based treatment recommendations. In this multinational, observational study we report 202 patients aged ≤25 years with A-T and hematological malignancies from 25 countries. Ninety-one patients (45%) presented with mature B-cell lymphomas, 82 (41%) with acute lymphoblastic leukemia/lymphoma, 21 (10%) with Hodgkin lymphoma and 8 (4%) with other hematological malignancies. Four-year overall survival and event-free survival (EFS) were 50.8% (95% confidence interval [CI], 43.6-59.1) and 47.9% (95% CI 40.8-56.2), respectively. Cure rates have not significantly improved over the last four decades (P = .76). The major cause of treatment failure was treatment-related mortality (TRM) with a four-year cumulative incidence of 25.9% (95% CI, 19.5-32.4). Germ line ATM PVs were categorized as null or hypomorphic and patients with available genetic data (n = 110) were classified as having absent (n = 81) or residual (n = 29) ATM kinase activity. Four-year EFS was 39.4% (95% CI, 29-53.3) vs 78.7% (95% CI, 63.7-97.2), (P < .001), and TRM rates were 37.6% (95% CI, 26.4-48.7) vs 4.0% (95% CI, 0-11.8), (P = .017), for those with absent and residual ATM kinase activity, respectively. Absence of ATM kinase activity was independently associated with decreased EFS (HR = 0.362, 95% CI, 0.16-0.82; P = .009) and increased TRM (hazard ratio [HR] = 14.11, 95% CI, 1.36-146.31; P = .029). Patients with A-T and leukemia/lymphoma may benefit from deescalated therapy for patients with absent ATM kinase activity and near-standard therapy regimens for those with residual kinase activity.

Unraveling the genetic and molecular landscape of sepsis and acute kidney injury: A comprehensive GWAS and machine learning approach

OBJECTIVES

This study aimed to explore the underlying mechanisms of sepsis and acute kidney injury (AKI), including sepsis-associated AKI (SA-AKI), a frequent complication in critically ill sepsis patients.

METHODS

GWAS data was analyzed for genetic association between AKI and sepsis. Then, we systematically applied three distinct machine learning algorithms (LASSO, SVM-RFE, RF) to rigorously identify and validate signature genes of SA-AKI, assessing their diagnostic and prognostic value through ROC curves and survival analysis. The study also examined the functional and immunological aspects of these genes, potential drug targets, and ceRNA networks. A mouse model of sepsis was created to test the reliability of these signature genes.

RESULTS

LDSC confirmed a positive genetic correlation between AKI and sepsis, although no significant shared loci were found. Bidirectional MR analysis indicated mutual increased risks of AKI and sepsis. Then, 311 key genes common to sepsis and AKI were identified, with 42 significantly linked to sepsis prognosis. Six genes, selected through LASSO, SVM-RFE, and RF algorithms, showed excellent predictive performance for sepsis, AKI, and SA-AKI. The models demonstrated near-perfect AUCs in both training and testing datasets, and a perfect AUC in a sepsis mouse model. Significant differences in immune cells, immune-related pathways, HLA, and checkpoint genes were found between high- and low-risk groups. The study identified 62 potential drug treatments for sepsis and AKI and constructed a ceRNA network.

CONCLUSIONS

The identified signature genes hold potential clinical applications, including prognostic evaluation and targeted therapeutic strategies for sepsis and AKI. However, further research is needed to confirm these findings.

Immune profiling and functional analysis of NK and T cells in ataxia telangiectasia

Ataxia telangiectasia (AT) is a rare autosomal-recessive disorder characterized by profound neurodegeneration, combined immunodeficiency, and an increased risk for malignant diseases. Treatment options for AT are limited, and the long-term survival prognosis for patients remains grim, primarily due to the emergence of chronic respiratory pathologies, malignancies, and neurological complications. Understanding the dysregulation of the immune system in AT is fundamental for the development of novel treatment strategies. In this context, we performed a retrospective longitudinal immunemonitoring of lymphocyte subset distribution in a cohort of AT patients (n = 65). Furthermore, we performed FACS analyses of peripheral blood mononuclear cells from a subgroup of 12 AT patients to examine NK and T cells for the expression of activating and functional markers. We observed reduced levels of peripheral blood CD3+CD8+ cytotoxic T cells, CD3+CD4+ T helper cells, and CD19+ B cells, whereas the amount of CD3--CD56+ NK cells and CD3+CD56+ NKT-like cells was similar compared with age-matched controls. Notably, there was no association between the age-dependent kinetic of T-, B-, or NK-cell counts and the occurrence of malignancy in AT patients. Additionally, our results indicate an altered NK- and T-cell response to cytokine stimulation in AT with increased levels of TRAIL, FasL, and CD16 expression in NK cells, as well as an elevated activation level of T cells in AT with notably higher expression levels of IFN-γ, CD107a, TRAIL, and FasL. Together, these findings imply function alterations in AT lymphocytes, specifically in T and NK cells, shedding light on potential pathways for innovative therapies.

Ataxia-Telangiectasia Mutated (ATM) gene signaling pathways in human cancers and their therapeutic implications

Cancer is a multifaceted disease driven by abnormal cell growth and poses a significant global health threat. The multifactorial causes, differences in individual susceptibility to therapeutic drugs, and induced drug resistance pose major challenges in addressing cancers effectively. One of the most important aspects in making cancers highly heterogeneous in their physiology lies in the genes involved and the changes occurring to some of these genes in malignant conditions. The Genetic factors have been implicated in the oncogenesis, progression, responses to treatment, and metastasis. One such gene that plays a key role in human cancers is the mutated form of the Ataxia-telangiectasia gene (ATM). ATM gene located on chromosome 11q23, plays a vital role in maintaining genomic stability. Understanding the genetic basis of A-T is crucial for diagnosis, management, and treatment. Breast cancer, lung cancer, prostate cancer, and gastric cancer exhibit varying relationships with the ATM gene and influence their pathways. Targeting the ATM pathway proves promising for enhancing treatment effectiveness, especially in conjunction with DNA damage response pathways. Analyzing the therapeutic consequences of ATM mutations, especially in these cancer types facilitates the approaches for early detection, intervention, development of personalized treatment approaches, and improved patient outcomes. This review emphasizes the role of the ATM gene in various cancers, highlighting its impact on DNA repair pathways and therapeutic responses.

Ataxia-telangiectasia in Latin America: clinical features, immunodeficiency, and mortality in a multicenter study

Ataxia-telangiectasia (AT) is a rare genetic disorder leading to neurological defects, telangiectasias, and immunodeficiency. We aimed to study the clinical and immunological features of Latin American patients with AT and analyze factors associated with mortality. Referral centers from 9 Latin American countries participated in this retrospective cohort study, and 218 patients were included.  Median (IQR) ages at symptom onset and diagnosis were 1.0 (1.0-2.0)  and 5.0 (3.0-8.0) years, respectively. Most patients presented recurrent airway infections, which was significantly associated with IgA deficiency. IgA deficiency was observed in 60.8% of patients and IgG deficiency in 28.6%. T- and B-lymphopenias were also present in most cases. Mean survival was 24.2 years, and Kaplan-Meier 20-year-survival rate was 52.6%, with higher mortality associated with female gender and low IgG levels. These findings suggest that immunologic status should be investigated in all patients with AT.

[Relevant cutaneous manifestations as indications for inborn errors of immunity]

Inborn errors of immunity (IEI) can affect different parts of the immune system and manifest especially through pathological infection susceptibility and immune dysregulation. Cutaneous manifestations of IEI can hint at the underlying immunodeficiency and the tendency for infection and inflammation. These manifestations can present as recurring eczema, erythema, abscesses, and hair loss with poor response to therapy. Cutaneous manifestations can be specific for certain IEI, or rather unspecific. Together with clinical course and severity, they can indicate the diagnosis. Early and accurate recognition, diagnosis, and treatment are crucial for optimizing patient outcomes. The diagnosis can be determined through a detailed patient history, clinical examination, and immunological diagnostics. Collaboration between immunologists and dermatologists is vital for comprehensive care and improvement of life quality.

Therapeutic strategies targeting cellular senescence for cancer and other diseases

Cellular senescence occurs in response to endogenous or exogenous stresses and is characterized by stable cell cycle arrest, alterations in nuclear morphology and secretion of proinflammatory factors, referred to as the senescence-associated secretory phenotype (SASP). An increase of senescent cells is associated with the development of several types of cancer and aging-related diseases. Therefore, senolytic agents that selectively remove senescent cells may offer opportunities for developing new therapeutic strategies against such cancers and aging-related diseases. This review outlines senescence inducers and the general characteristics of senescent cells. We also discuss the involvement of senescent cells in certain cancers and diseases. Finally, we describe a series of senolytic agents and their utilization in therapeutic strategies.

Ataxia and Hypogonadism: a Review of the Associated Genes and Syndromes

The association of hypogonadism and cerebellar ataxia was first recognized in 1908 by Gordon Holmes. Since the seminal description, several heterogeneous phenotypes have been reported, differing for age at onset, associated features, and gonadotropins levels. In the last decade, the genetic bases of these disorders are being progressively uncovered. Here, we review the diseases associating ataxia and hypogonadism and the corresponding causative genes. In the first part of this study, we focus on clinical syndromes and genes (RNF216, STUB1, PNPLA6, AARS2, SIL1, SETX) predominantly associated with ataxia and hypogonadism as cardinal features. In the second part, we mention clinical syndromes and genes (POLR3A, CLPP, ERAL1, HARS, HSD17B4, LARS2, TWNK, POLG, ATM, WFS1, PMM2, FMR1) linked to complex phenotypes that include, among other features, ataxia and hypogonadism. We propose a diagnostic algorithm for patients with ataxia and hypogonadism, and we discuss the possible common etiopathogenetic mechanisms.

ATM deficiency differentially affects expression of proteins related to fatty acid oxidation and oxidative stress in a sex-specific manner in response to Western-type diet prior to and following myocardial infarction

AIMS

Published work has shown that ataxia-telangiectasia mutated kinase (ATM) deficiency is associated with cardioprotective effects in Western-type diet (WD)-fed female mice. This study assessed the expression of proteins related to fatty acid oxidation (FAO) and oxidative stress in WD-fed male and female mouse hearts, and investigated if sex-specific cardioprotective effects in WD-fed female ATM-deficient mice are maintained following myocardial infarction (MI).

MAIN METHODS

Wild-type (WT) and ATM-deficient (hKO) mice (both sexes) were placed on WD for 14 weeks. Myocardial tissue from a subset of mice was used for western blot analyses, while another subset of WD-fed mice underwent MI. Heart function was analyzed by echocardiography prior to and 1 day post-MI.

KEY FINDINGS

CPT1B (mitochondrial FAO enzyme) expression was lower in male hKO-WD, while it was higher in female hKO-WD vs WT-WD. WD-mediated decrease in ACOX1 (peroxisomal FAO enzyme) expression was only observed in male WT-WD. PMP70 (transports fatty acyl-CoA across peroxisomal membrane) expression was lower in male hKO-WD vs WT-WD. Catalase (antioxidant enzyme) expression was higher, while Nox4 (pro-oxidant enzyme) expression was lower in female hKO-WD vs WT-WD. Heart function was better in female hKO-WD vs WT-WD. However, post-MI heart function was not significantly different among all MI groups. Post-MI, CPT1B and catalase expression was higher in male hKO-WD-MI vs WT-WD-MI, while Nox4 expression was higher in female hKO-WD-MI vs WT-WD-MI.

SIGNIFICANCE

Increased mitochondrial FAO and decreased oxidative stress contribute towards ATM deficiency-mediated cardioprotective effects in WD-fed female mice which are abolished post-MI with increased Nox4 expression.

Ataxia telangiectasia: a rare case report from Nepal

Introduction and importance

Ataxia telangiectasia (A-T) is a rare autosomal recessive neurodegenerative disorder with early childhood onset. It is characterized by ataxia, oculocutaneous telangiectasia, immunodeficiency, and lymphoid-origin cancer predisposition due to ataxia telangiectasia mutated gene mutations.

Case presentation

The authors present a 19-year-old girl with spastic movements since 18 months, leading to wheelchair dependence. Ocular telangiectasia, dystonic posture, and slurred speech were evident. Diagnosis involved elevated alpha-fetoprotein levels and typical brain imaging.

Clinical discussion

A-T due to ataxia telangiectasia mutated gene mutations located on chromosome 11q22-23. It has varied presentations categorized by age and features. Timely diagnosis relies on characteristic symptoms, lab findings, and imaging. Radiation sensitivity and increased cancer risk underscore cautious radiation use.

Conclusion

A-T is a complex disorder with no cure. Genetic counseling for parents is vital. Its poor prognosis due to infection susceptibility and cancer risk necessitates supportive care. Comprehensive management, including genetic counseling and careful surveillance, is imperative.

Somatic Versus Germline: A Case Series of Three Children With ATM-Mutated Medulloblastoma

Somatic versus Germline-A Case Series of Three Children with ATM- mutated Medulloblastoma.

Identification of Two Novel Pathogenic Variants of the ATM Gene in the Iranian-Azeri Turkish Ethnic Group by Applying Whole Exome Sequencing

Background

The ATM gene encodes a multifunctional kinase involved in important cellular functions, such as checkpoint signaling and apoptosis, in response to DNA damage. Bi-allelic pathogenic variants in this gene cause Ataxia Telangiectasia (AT), while carriers of ATM pathogenic variants are at increased risk of cancer depending on the pathogenicity of the variant they carry. Identifying pathogenic variants can aid in the management of the disease in carriers.

Methods

Whole-exome sequencing (WES) was performed on three unrelated patients from the Iranian-Azeri Turkish ethnic group referred to a genetic center for analysis. WES was also conducted on 400 individuals from the same ethnic group to determine the frequencies of all ATM variants. Blood samples were collected from the patients and their family members for DNA extraction, and PCR-Sanger sequencing was performed to confirm the WES results.

Results

The first proband with AT disease had two novel compound heterozygote variants (c.2639-2A>T, c.8708delC) in the ATM gene revealed by WES analysis, which was potentially/likely pathogenic. The second proband with bi-lateral breast cancer had a homozygous pathogenic variant (c.6067G>A) in the ATM gene identified by WES analysis. The third case with a family history of cancer had a heterozygous synonymous pathogenic variant (c.7788G>A) in the ATM gene found by WES analysis. Sanger sequencing confirmed the WES results, and bioinformatics analysis of the mutated ATM RNA and protein structure added evidence for the potential pathogenicity of the novel variants. WES analysis of the cohort revealed 38 different variants, including a variant (rs1800057, ATM:c.3161C>G, p.P1054R) associated with prostate cancer that had a higher frequency in our cohort.

Conclusion

Genetic analysis of three unrelated families with ATM-related disorders discovered two novel pathogenic variants. A homozygous missense pathogenic variant was identified in a woman with bi-lateral breast cancer, and a synonymous but pathogenic variant was found in a family with a history of different cancers.

Genetic Testing Enhances the Precision Diagnosis and Treatment of Breast Cancer

The contemporary comprehension of breast cancer has progressed to the molecular level. As a heterogeneous malignancy, conventional pathological diagnosis and histological classification could no longer meet the needs of precisely managing breast cancer. Genetic testing based on gene expression profiles and gene mutations has emerged and substantially contributed to the precise diagnosis and treatment of breast cancer. Multigene assays (MGAs) are explored for early-stage breast cancer patients, aiding the selection of adjuvant therapy and predicting prognosis. For metastatic breast cancer patients, testing specific genes indicates potentially effective antitumor agents. In this review, genetic testing in early-stage and metastatic breast cancer is summarized, as well as the advantages and challenges of genetic testing in breast cancer.

Expression of a large coding sequence: Gene therapy vectors for Ataxia Telangiectasia

Ataxia telangiectasia is a monogenetic disorder caused by mutations in the ATM gene. Its encoded protein kinase ATM plays a fundamental role in DNA repair of double strand breaks (DSBs). Impaired function of this kinase leads to a multisystemic disorder including immunodeficiency, progressive cerebellar degeneration, radiation sensitivity, dilated blood vessels, premature aging and a predisposition to cancer. Since allogenic hematopoietic stem cell (HSC) transplantation improved disease outcome, gene therapy based on autologous HSCs is an alternative promising concept. However, due to the large cDNA of ATM (9.2 kb), efficient packaging of retroviral particles and sufficient transduction of HSCs remains challenging.We generated lentiviral, gammaretroviral and foamy viral vectors with a GFP.F2A.Atm fusion or a GFP transgene and systematically compared transduction efficiencies. Vector titers dropped with increasing transgene size, but despite their described limited packaging capacity, we were able to produce lentiviral and gammaretroviral particles. The reduction in titers could not be explained by impaired packaging of the viral genomes, but the main differences occurred after transduction. Finally, after transduction of Atm-deficient (ATM-KO) murine fibroblasts with the lentiviral vector expressing Atm, we could show the expression of ATM protein which phosphorylated its downstream substrates (pKap1 and p-p53).

Understanding the Ultra-Rare Disease Autosomal Dominant Leukodystrophy: an Updated Review on Morpho-Functional Alterations Found in Experimental Models

Autosomal dominant leukodystrophy (ADLD) is an ultra-rare, slowly progressive, and fatal neurodegenerative disorder associated with the loss of white matter in the central nervous system (CNS). Several years after its first clinical description, ADLD was found to be caused by coding and non-coding variants in the LMNB1 gene that cause its overexpression in at least the brain of patients. LMNB1 encodes for Lamin B1, a protein of the nuclear lamina. Lamin B1 regulates many cellular processes such as DNA replication, chromatin organization, and senescence. However, its functions have not been fully characterized yet. Nevertheless, Lamin B1 together with the other lamins that constitute the nuclear lamina has firstly the key role of maintaining the nuclear structure. Being the nucleus a dynamic system subject to both biochemical and mechanical regulation, it is conceivable that changes to its structural homeostasis might translate into functional alterations. Under this light, this review aims at describing the pieces of evidence that to date have been obtained regarding the effects of LMNB1 overexpression on cellular morphology and functionality. Moreover, we suggest that further investigation on ADLD morpho-functional consequences is essential to better understand this complex disease and, possibly, other neurological disorders affecting CNS myelination.

Reduced expression of phosphorylated ataxia-telangiectasia mutated gene is related to poor prognosis and gemcitabine chemoresistance in pancreatic cancer

BACKGROUND

Loss of expression of the gene ataxia-telangiectasia mutated (ATM), occurring in patients with multiple primary malignancies, including pancreatic cancer, is associated with poor prognosis. In this study, we investigated the detailed molecular mechanism through which ATM expression affects the prognosis of patients with pancreatic cancer.

METHODS

The levels of expression of ATM and phosphorylated ATM in patients with pancreatic cancer who had undergone surgical resection were analyzed using immunohistochemistry staining. RNA sequencing was performed on ATM-knockdown pancreatic-cancer cells to elucidate the mechanism underlying the invlovement of ATM in pancreatic cancer.

RESULTS

Immunohistochemical analysis showed that 15.3% and 27.8% of clinical samples had low levels of ATM and phosphorylated ATM, respectively. Low expression of phosphorylated ATM substantially reduced overall and disease-free survival in patients with pancreatic cancer. In the pancreatic cancer cell lines with ATM low expression, resistance to gemcitabine was demonstrated. The RNA sequence demonstrated that ATM knockdown induced the expression of MET and NTN1. In ATM knockdown cells, it was also revealed that the protein expression levels of HIF-1α and antiapoptotic BCL-2/BAD were upregulated.

CONCLUSIONS

These findings demonstrate that loss of ATM expression increases tumor development, suppresses apoptosis, and reduces gemcitabine sensitivity. Additionally, loss of phosphorylated ATM is associated with a poor prognosis in patients with pancreatic cancer. Thus, phosphorylated ATM could be a possible target for pancreatic cancer treatment as well as a molecular marker to track patient prognosis.

[Progeroid syndromes : Aging, skin aging, and mechanisms of progeroid syndromes]

Progeroid syndromes (PSs) are characterized by the premature onset of age-related pathologies. PSs display a wide range of heterogeneous pathological symptoms that also manifest during natural aging, including vision and hearing loss, atrophy, hair loss, progressive neurodegeneration, and cardiovascular defects. Recent advances in molecular pathology have led to a better understanding of the underlying mechanisms of these diseases. The genetic mutations underlying PSs are functionally linked to genome maintenance and repair, supporting the causative role of DNA damage accumulation in aging. While some of those genes encode proteins with a direct involvement in a DNA repair machinery, such as nucleotide excision repair (NER), others destabilize the genome by compromising the stability of the nuclear envelope, when lamin A is dysfunctional in Hutchinson-Gilford progeria syndrome (HGPS) or regulate the DNA damage response (DDR) such as the ataxia telangiectasia-mutated (ATM) gene. Understanding the molecular pathology of progeroid diseases is crucial in developing potential treatments to manage and prevent the onset of symptoms. This knowledge provides insight into the underlying mechanisms of premature aging and could lead to improved quality of life for individuals affected by progeroid diseases.

Ataxia-telangiectasia in China: a case report of a novel ATM variant and literature review

Background

Ataxia-telangiectasia (A-T) is a multisystem genetic disorder involving ataxia, oculocutaneous telangiectasia, and immunodeficiency caused by biallelic pathogenic variants in the ATM gene. To date, most ATM variants have been reported in the Caucasian population, and few studies have focused on the genotype-phenotype correlation of A-T in the Chinese population. We herein present a Chinese patient with A-T who carries compound heterozygous variants in the ATM gene and conducted a literature review for A-T in China.

Case presentation

A 7-year-old Chinese girl presented with growth retardation, ataxia, medium ocular telangiectasia, cerebellar atrophy, and elevated serum alpha-fetoprotein (AFP) level, which supported the suspicion of A-T. Notably, the serum levels of immunoglobulins were all normal, ruling out immunodeficiency. Exome sequencing and Sanger sequencing revealed two likely pathogenic ATM variants, namely NM_000051.4: c.4195dup (p.Thr1399Asnfs*15) and c.6006 + 1G>T (p.?), which were inherited from her father and mother, respectively. From the Chinese literature review, we found that there was a marked delay in the diagnosis of A-T, and 38.9% (7/18) of A-T patients did not suffer from immunodeficiency in China. No genotype-phenotype correlation was observed in this group of A-T patients.

Conclusion

These results extend the genotype spectrum of A-T in the Chinese population and imply that the diagnosis of A-T in China should be improved.

Rapid and precise genotyping of transgene zygosity in mice using an allele-specific method

Precise determination of transgene zygosity is essential for use of transgenic mice in research. Because integration loci of transgenes are usually unknown due to their random insertion, assessment of transgene zygosity remains a challenge. Current zygosity genotyping methods (progeny testing, qPCR, and NGS-computational biology analysis) are time consuming, prone to error or technically challenging. Here, we developed a novel method to determine transgene zygosity requiring no knowledge of transgene insertion loci. This method applies allele-specific restriction enzyme digestion of PCR products (RE/PCR) to rapidly and reliably quantify transgene zygosity. We demonstrate the applicability of this method to three transgenic strains of mice (Atm TgC3001L, Nes-Cre, and Syn1-Cre) harboring a unique restriction enzyme site on either the transgene or its homologous sequence in the mouse genome. This method is as accurate as the gold standard of progeny testing but requires 2 d instead of a month or more. It is also exceedingly more accurate than the most commonly used approach of qPCR quantification. Our novel method represents a significant technical advance in determining transgene zygosities in mice.

Genome-Wide Screening in Human Embryonic Stem Cells Highlights the Hippo Signaling Pathway as Granting Synthetic Viability in ATM Deficiency

ATM depletion is associated with the multisystemic neurodegenerative syndrome ataxia-telangiectasia (A-T). The exact linkage between neurodegeneration and ATM deficiency has not been established yet, and no treatment is currently available. In this study, we aimed to identify synthetic viable genes in ATM deficiency to highlight potential targets for the treatment of neurodegeneration in A-T. We inhibited ATM kinase activity using the background of a genome-wide haploid pluripotent CRISPR/Cas9 loss-of-function library and examined which mutations confer a growth advantage on ATM-deficient cells specifically. Pathway enrichment analysis of the results revealed the Hippo signaling pathway as a major negative regulator of cellular growth upon ATM inhibition. Indeed, genetic perturbation of the Hippo pathway genes SAV1 and NF2, as well as chemical inhibition of this pathway, specifically promoted the growth of ATM-knockout cells. This effect was demonstrated in both human embryonic stem cells and neural progenitor cells. Therefore, we suggest the Hippo pathway as a candidate target for the treatment of the devastating cerebellar atrophy associated with A-T. In addition to the Hippo pathway, our work points out additional genes, such as the apoptotic regulator BAG6, as synthetic viable with ATM-deficiency. These genes may help to develop drugs for the treatment of A-T patients as well as to define biomarkers for resistance to ATM inhibition-based chemotherapies and to gain new insights into the ATM genetic network.

Can accelerated ageing models inform us on age-related tauopathies?

Ageing is the greatest risk factor of late-onset neurodegenerative diseases. In the realm of sporadic tauopathies, modelling the process of biological ageing in experimental animals forms the foundation of searching for the molecular origin of pathogenic tau and developing potential therapeutic interventions. Although prior research into transgenic tau models offers valuable lessons for studying how tau mutations and overexpression can drive tau pathologies, the underlying mechanisms by which ageing leads to abnormal tau accumulation remains poorly understood. Mutations associated with human progeroid syndromes have been proposed to be able to mimic an aged environment in animal models. Here, we summarise recent attempts in modelling ageing in relation to tauopathies using animal models that carry mutations associated with human progeroid syndromes, or genetic elements unrelated to human progeroid syndromes, or have exceptional natural lifespans, or a remarkable resistance to ageing-related disorders.

Infections in Inborn Errors of Immunity with Combined Immune Deficiency: A Review

Enhanced susceptibility to microbes, often resulting in severe, intractable and frequent infections due to usually innocuous organisms at uncommon sites, is the most striking feature in individuals with an inborn error of immunity. In this narrative review, based on the International Union of Immunological Societies' 2022 (IUIS 2022) Update on phenotypic classification of human inborn errors of immunity, the focus is on commonly encountered Combined Immunodeficiency Disorders (CIDs) with susceptibility to infections. Combined immune deficiency disorders are usually commensurate with survival beyond infancy unlike Severe Combined Immune Deficiency (SCID) and are often associated with clinical features of a syndromic nature. Defective humoral and cellular immune responses result in susceptibility to a broad range of microbial infections. Although disease onset is usually in early childhood, mild defects may present in late childhood or even in adulthood. A precise diagnosis is imperative not only for determining management strategies, but also for providing accurate genetic counseling, including prenatal diagnosis, and also in deciding empiric treatment of infections upfront before investigation reports are available.

Peripheral neuropathies associated with DNA repair disorders

Repair of genomic DNA is a fundamental housekeeping process that quietly maintains the health of our genomes. The consequences of a genetic defect affecting a component of this delicate mechanism are quite harmful, characterized by a cascade of premature aging that injures a variety of organs, including the nervous system. One part of the nervous system that is impaired in certain DNA repair disorders is the peripheral nerve. Chronic motor, sensory, and sensorimotor polyneuropathies have all been observed in affected individuals, with specific physiologies associated with different categories of DNA repair disorders. Cockayne syndrome has classically been linked to demyelinating polyneuropathies, whereas xeroderma pigmentosum has long been associated with axonal polyneuropathies. Three additional recessive DNA repair disorders are associated with neuropathies, including trichothiodystrophy, Werner syndrome, and ataxia-telangiectasia. Although plausible biological explanations exist for why the peripheral nerves are specifically vulnerable to impairments of DNA repair, specific mechanisms such as oxidative stress remain largely unexplored in this context, and bear further study. It is also unclear why different DNA repair disorders manifest with different types of neuropathy, and why neuropathy is not universally present in those diseases. Longitudinal physiological monitoring of these neuropathies with serial electrodiagnostic studies may provide valuable noninvasive outcome data in the context of future natural history studies, and thus the responses of these neuropathies may become sentinel outcome measures for future clinical trials of treatments currently in development such as adeno-associated virus gene replacement therapies.

White blood cell count and chronic obstructive pulmonary disease: A Mendelian Randomization study

Blood leukocyte counts (e.g., eosinophil count) are important biomarkers for the onset, classification, and exacerbation of chronic obstructive pulmonary disease (COPD). The causal relationships between them are necessary for the development of COPD treatment strategy, but remain unclear. Here, we implement two-sample bi-directional univariable Mendelian Randomization (MR) and multivariable MR to investigate the causal relationships. Univariable MR find that elevated blood eosinophil count significantly increases the risk of COPD (odds ratio (OR) = 1.22, 95% confidence interval (CI): 1.14-1.30, P = 1.54 × 10^-09) and COPD-related hospitalization (OR = 1.44, 95% CI: 1.15-1.80, P = 1.36 × 10^-03). Besides, it also significantly decreases the ratio of forced expiratory volume in the first second over forced vital capacity (FEV₁/FVC ratio) (OR = 0.942, 95% CI: 0.914-0.971, P = 1.02 × 10^-04). These findings are fully supported by multivariate MR results. Interestingly, univariable MR reveals a weak causal relationship between elevated blood eosinophil count and COPD risk in younger people (<65 years) (OR = 1.39, 95% CI: 1.10-1.75, P = 5.52 × 10^-03), but not older individuals (OR = 1.20, 95% CI: 0.926-1.55, P = 0.17). Finally, reverse univariable MR reveals the onset of COPD and the decreased FEV₁/FVC ratio both lead to increased blood neutrophil count (OR = 1.03, 95% CI: 1.01-1.05, P = 3.40 × 10^-03 and OR = 0.947, 95% CI: 0.91-0.986, P = 8.75 × 10^-03 respectively). In summary, this MR study demonstrates that high blood eosinophil count is an independent causal mediator of COPD risk, FEV₁/FVC decline, and COPD-related hospitalization. The increase in neutrophil count is induced by COPD onset or FEV₁/FVC decline. This suggests eosinophil, but not neutrophil, may be used as a therapeutic target for preventing the onset and exacerbation of COPD and FEV₁/FVC decline. Therefore, a non-neutrophil-targeted therapeutic strategy for neutrophilic COPD is required in the future.

Concurrent intraventricular intracranial myxoid mesenchymal tumor and ependymoma in a long-term Ewing sarcoma survivor

Intracranial myxoid mesenchymal tumor, FET::CREB fusion positive is a rare, recently described central nervous system neoplasm. It is characterized by EWSR1::CREB family transcription factor fusion, typically arises in children and adolescents, and is locally aggressive even after gross total resection. Currently, there are little data available to guide management and gauge long-term prognosis. Furthermore, there have been no reports of these lesions occurring simultaneously with other intracranial neoplasms or in patients with a history of malignancy. Here we describe the first case of a very unusual patient with intracranial myxoid mesenchymal tumor of the right lateral ventricle with a concurrent fourth ventricular ependymoma who had a remote history of Ewing sarcoma of the right fibula.

DNA Repair Mechanisms, Protein Interactions and Therapeutic Targeting of the MRN Complex

Repair of a DNA double-strand break relies upon a pathway of proteins to identify damage, regulate cell cycle checkpoints, and repair the damage. This process is initiated by a sensor protein complex, the MRN complex, comprised of three proteins-MRE11, RAD50, and NBS1. After a double-stranded break, the MRN complex recruits and activates ATM, in-turn activating other proteins such as BRCA1/2, ATR, CHEK1/2, PALB2 and RAD51. These proteins have been the focus of many studies for their individual roles in hereditary cancer syndromes and are included on several genetic testing panels. These panels have enabled us to acquire large amounts of genetic data, much of which remains a challenge to interpret due to the presence of variants of uncertain significance (VUS). While the primary aim of clinical testing is to accurately and confidently classify variants in order to inform medical management, the presence of VUSs has led to ambiguity in genetic counseling. Pathogenic variants within MRN complex genes have been implicated in breast, ovarian, prostate, colon cancers and gliomas; however, the hundreds of VUSs within MRE11, RAD50, and NBS1 precludes the application of these data in genetic guidance of carriers. In this review, we discuss the MRN complex's role in DNA double-strand break repair, its interactions with other cancer predisposing genes, the variants that can be found within the three MRN complex genes, and the MRN complex's potential as an anti-cancer therapeutic target.

Deficiency of ataxia-telangiectasia mutated kinase attenuates Western-type diet-induced cardiac dysfunction in female mice

Chronic consumption of Western-type diet (WD) induces cardiac structural and functional abnormalities. Previously, we have shown that WD consumption in male ATM (ataxia-telangiectasia mutated kinase) deficient mice associates with accelerated body weight (BW) gain, cardiac systolic dysfunction with increased preload, and exacerbation of hypertrophy, apoptosis, and inflammation. This study investigated the role of ATM deficiency in WD-induced changes in functional and biochemical parameters of the heart in female mice. Six-week-old wild-type (WT) and ATM heterozygous knockout (hKO) female mice were placed on WD or NC (normal chow) for 14 weeks. BW gain, fat accumulation, and cardiac functional and biochemical parameters were measured 14 weeks post-WD. WD-induced subcutaneous and total fat contents normalized to body weight were higher in WT-WD versus hKO-WD. Heart function measured using echocardiography revealed decreased percent fractional shortening and ejection fraction, and increased LV end systolic diameter and volume in WT-WD versus WT-NC. These functional parameters remained unchanged in hKO-WD versus hKO-NC. Myocardial fibrosis, myocyte hypertrophy, and apoptosis were higher in WT-WD versus WT-NC. However, apoptosis was significantly lower and hypertrophy was significantly higher in hKO-WD versus WT-WD. MMP-9 and Bax expression, and Akt activation were higher in WT-WD versus WT-NC. PARP-1 (full-length) expression and mTOR activation were lower in WT-WD versus hKO-WD. Thus, ATM deficiency in female mice attenuates fat weight gain, preserves heart function, and associates with decreased cardiac cell apoptosis in response to WD.

Inborn errors of immunity associated with defects of thymic development

The main function of the thymus is to support the establishment of a wide repertoire of T lymphocytes capable of eliminating foreign pathogens, yet tolerant to self-antigens. Thymocyte development in the thymus is dependent on the interaction with thymic stromal cells, a complex mixture of cells comprising thymic epithelial cells (TEC), mesenchymal and endothelial cells. The exchange of signals between stromal cells and thymocytes is referred to as "thymic cross-talk". Genetic defects affecting either side of this interaction result in defects in thymic development that ultimately lead to a decreased output of T lymphocytes to the periphery. In the present review, we aim at providing a summary of inborn errors of immunity (IEI) characterized by T-cell lymphopenia due to defects of the thymic stroma, or to hematopoietic-intrinsic defects of T-cell development, with a special focus on recently discovered disorders. Additionally, we review the novel diagnostic tools developed to discover and study new genetic causes of IEI due to defects in thymic development. Finally, we discuss therapeutic approaches to correct thymic defects that are currently available, in addition to potential novel therapies that could be applied in the future.

Mitophagy: An Emergence of New Player in Alzheimer’s Disease

Mitochondria provide neurons not only energy as ATP to keep them growing, proliferating and developing, but they also control apoptosis. Due to their high bioenergetic demand, neurons which are highly specific terminally differentiated cells, essentially depend on mitochondria. Defective mitochondrial function is thus related to numerous age-linked neurodegenerative ailments like Alzheimer’s disease (AD), in which the build-up of impaired and malfunctioning mitochondria has been identified as a primary sign, paying to disease development. Mitophagy, selective autophagy, is a key mitochondrial quality control system that helps neurons to stay healthy and functional by removing undesired and damaged mitochondria. Dysfunctional mitochondria and dysregulated mitophagy have been closely associated with the onset of ADs. Various proteins associated with mitophagy were found to be altered in AD. Therapeutic strategies focusing on the restoration of mitophagy capabilities could be utilized to strike the development of AD pathogenesis. We summarize the mechanism and role of mitophagy in the onset and advancement of AD, in the quality control mechanism of mitochondria, the consequences of dysfunctional mitophagy in AD, and potential therapeutic approaches involving mitophagy modulation in AD. To develop new therapeutic methods, a better knowledge of the function of mitophagy in the pathophysiology of AD is required.

Genomics Driving Diagnosis and Treatment of Inborn Errors of Immunity With Cancer Predisposition

Inborn errors of immunity (IEI) are genetically and clinically heterogeneous disorders that, in addition to infection susceptibility and immune dysregulation, can have an enhanced cancer predisposition. The increasing availability of upfront next-generation sequencing diagnostics in immunology and oncology have uncovered substantial overlap of germline and somatic genetic conditions that can result in immunodeficiency and cancer. However, broad application of unbiased genetics in these neighboring disciplines still needs to be deployed, and joined therapeutic strategies guided by germline and somatic genetic risk factors are lacking. We illustrate the current difficulties encountered in clinical practice, summarize the historical development of pathophysiological concepts of cancer predisposition, and review select genetic, molecular, and cellular mechanisms of well-defined and illustrative disease entities such as DNA repair defects, combined immunodeficiencies with Epstein-Barr virus susceptibility, autoimmune lymphoproliferative syndromes, regulatory T-cell disorders, and defects in cell intrinsic immunity. We review genetic variants that, when present in the germline, cause IEI with cancer predisposition but, when arising as somatic variants, behave as oncogenes and cause specific cancer entities. We finally give examples of small molecular compounds that are developed and studied to target genetically defined cancers but might also proof useful to treat IEI.

C. elegans as an Animal Model to Study the Intersection of DNA Repair, Aging and Neurodegeneration

Since its introduction as a genetic model organism, Caenorhabditis elegans has yielded insights into the causes of aging. In addition, it has provided a molecular understanding of mechanisms of neurodegeneration, one of the devastating effects of aging. However, C. elegans has been less popular as an animal model to investigate DNA repair and genomic instability, which is a major hallmark of aging and also a cause of many rare neurological disorders. This article provides an overview of DNA repair pathways in C. elegans and the impact of DNA repair on aging hallmarks, such as mitochondrial dysfunction, telomere maintenance, and autophagy. In addition, we discuss how the combination of biological characteristics, new technical tools, and the potential of following precise phenotypic assays through a natural life-course make C. elegans an ideal model organism to study how DNA repair impact neurodegeneration in models of common age-related neurodegenerative diseases.

DNA double-strand break repair and nucleic acid-related immunity

DNA damage repair and innate immunity are two conserved mechanisms that both function in cellular stress responses. Recently, an increasing amount of evidence has uncovered the close relationship between these two ancient biological processes. Here, we review the classical function of factors involved in DNA repair, and especially double-strand break repair, in innate immunity; more importantly, we discuss the novel roles of DNA repair factors in regulating innate immunity and vice versa. In addition, we also review the roles of DNA repair, innate immunity and their crosstalk in human diseases, which suggest that these two pathways may be compelling targets for disease prevention and treatment.

Progressive Depletion of B and T Lymphocytes in Patients with Ataxia Telangiectasia: Results of the Italian Primary Immunodeficiency Network

Ataxia telangiectasia (AT) is a rare neurodegenerative genetic disorder due to bi-allelic mutations in the Ataxia Telangiectasia Mutated (ATM) gene. The aim of this paper is to better define the immunological profile over time, the clinical immune-related manifestations at diagnosis and during follow-up, and to attempt a genotype-phenotype correlation of an Italian cohort of AT patients. Retrospective data of 69 AT patients diagnosed between December 1984 and November 2019 were collected from the database of the Italian Primary Immunodeficiency Network. Patients were classified at diagnosis as lymphopenic (Group A) or non-lymphopenic (Group B). Fifty eight out of 69 AT patients (84%) were genetically characterized and distinguished according to the type of mutations in truncating/truncating (TT; 27 patients), non-truncating (NT)/T (28 patients), and NT/NT (5 patients). In 3 patients, only one mutation was detected. Data on age at onset and at diagnosis, cellular and humoral compartment at diagnosis and follow-up, infectious diseases, signs of immune dysregulation, cancer, and survival were analyzed and compared to the genotype. Lymphopenia at diagnosis was related per se to earlier age at onset. Progressive reduction of cellular compartment occurred during the follow-up with a gradual reduction of T and B cell number. Most patients of Group A carried bi-allelic truncating mutations, had a more severe B cell lymphopenia, and a reduced life expectancy. A trend to higher frequency of interstitial lung disease, immune dysregulation, and malignancy was noted in Group B patients. Lymphopenia at the onset and the T/T genotype are associated with a worst clinical course. Several mechanisms may underlie the premature and progressive immune decline in AT subjects.

Genome Integrity and Neurological Disease

Neurological complications directly impact the lives of hundreds of millions of people worldwide. While the precise molecular mechanisms that underlie neuronal cell loss remain under debate, evidence indicates that the accumulation of genomic DNA damage and consequent cellular responses can promote apoptosis and neurodegenerative disease. This idea is supported by the fact that individuals who harbor pathogenic mutations in DNA damage response genes experience profound neuropathological manifestations. The review article here provides a general overview of the nervous system, the threats to DNA stability, and the mechanisms that protect genomic integrity while highlighting the connections of DNA repair defects to neurological disease. The information presented should serve as a prelude to the Special Issue “Genome Stability and Neurological Disease”, where experts discuss the role of DNA repair in preserving central nervous system function in greater depth.

The natural history of ataxia-telangiectasia (A-T): A systematic review

BACKGROUND

Ataxia-telangiectasia is an autosomal recessive, multi-system, and life-shortening disease caused by mutations in the ataxia-telangiectasia mutated gene. Although widely reported, there are no studies that give a comprehensive picture of this intriguing condition.

OBJECTIVES

Understand the natural history of ataxia-telangiectasia (A-T), as reported in scientific literature.

SEARCH METHODS

107 search terms were identified and divided into 17 searches. Each search was performed in PubMed, Ovid SP (MEDLINE) 1946-present, OVID EMBASE 1980 -present, Web of Science core collection, Elsevier Scopus, and Cochrane Library.

SELECTION CRITERIA

All human studies that report any aspect of A-T.

DATA COLLECTION AND ANALYSIS

Search results were de-duplicated, data extracted (including author, publication year, country of origin, study design, population, participant characteristics, and clinical features). Quality of case-control and cohort studies was assessed by the Newcastle-Ottawa tool. Findings are reported descriptively and where possible data collated to report median (interquartile range, range) of outcomes of interest.

MAIN RESULTS

1314 cases reported 2134 presenting symptoms. The most common presenting symptom was abnormal gait (1160 cases; 188 studies) followed by recurrent infections in classical ataxia-telangiectasia and movement disorders in variant ataxia-telangiectasia. 687 cases reported 752 causes of death among which malignancy was the most frequently reported cause. Median (IQR, range) age of death (n = 294) was 14 years 0 months (10 years 0 months to 23 years 3 months, 1 year 3 months to 76 years 0 months).

CONCLUSIONS

This review demonstrates the multi-system involvement in A-T, confirms that neurological symptoms are the most frequent presenting features in classical A-T but variants have diverse manifestations. We found that most individuals with A-T have life limited to teenage or early adulthood. Predominance of case reports, and case series demonstrate the lack of robust evidence to determine the natural history of A-T. We recommend population-based studies to fill this evidence gap.

Practical Genetics for the Neuroradiologist: Adding Value in Neurogenetic Disease

Genetic discoveries have transformed our understanding of many neurologic diseases. Identification of specific causal pathogenic variants has improved understanding of pathophysiology and enabled replacement of many confusing eponyms and acronyms with more meaningful and clinically relevant genetics-based terminology. In this era of rapid scientific advancement, multidisciplinary collaboration among pediatricians, neurologists, geneticists, radiologists, and other members of the health care team is increasingly important in the care of patients with genetic neurologic diseases. Radiologists familiar with neurogenetic disease add value by (1) recognizing constellations of characteristic imaging findings that are associated with a genetic disease before one is clinically suspected; (2) predicting the most likely genotypes for a given imaging phenotype in clinically suspected genetic disease; and (3) providing detailed and accurate descriptions of the imaging phenotype in challenging cases with unknown or uncertain genotypes. This review aims to increase awareness and understanding of pathogenic variants relating to neurologic disease by (1) briefly reviewing foundational knowledge of chromosomes, inheritance patterns, and mutagenesis; (2) providing concrete examples of and detailed information about specific neurologic diseases resulting from pathogenic variants; and (3) highlighting clinical and imaging features that are of greatest relevance for the radiologist.

Genetics and Emerging Therapies for Brain Arteriovenous Malformations

Brain arteriovenous malformations (AVMs) are characterized by a high-pressure, low-resistance vascular nidus created by direct shunting of blood from feeding arteries into arterialized veins, bypassing intervening capillaries. AVMs pose a risk of spontaneous rupture because the vessel walls are continuously exposed to increased shear stress and abnormal flow phenomena, which lead to vessel wall inflammation and distinct morphologic changes. The annual rupture rate is estimated at 2%, and once an AVM ruptures, the risk of rerupture increases 5-fold. The ability of AVMs to grow, regress, recur, and undergo remodeling shows their dynamic nature. Identifying the underlying cellular and molecular pathways of AVMs not only helps us understand their natural physiology but also allows us to directly block vital pathways, thus preventing AVM development and progression. Management of AVMs is challenging and often necessitates a multidisciplinary approach, including neurosurgical, endovascular, and radiosurgical expertise. Because many of these procedures are invasive, carry a risk of inciting hemorrhage, or are controversial, the demand for pharmacologic treatment options is increasing. In this review, we introduce novel findings of cellular and molecular AVM physiology and highlight key signaling mediators that are potential targets for AVM treatment. Furthermore, we give an overview of syndromes associated with hereditary and nonhereditary AVM formation and discuss causative genetic alterations.

Evaluation of Specific Antibody Responses in Patients with Selective IgA Deficiency and Ataxia Telangiectasia

BACKGROUND

Specific Antibody Deficiency (SAD) is a primary immunodeficiency disease (PID) characterized by the occurrence of recurrent infections and inadequate antibody response to polysaccharide new antigens.

OBJECTIVE

This study aims to determine the titer of specific antibodies against unconjugated 23-valent pneumococcal polysaccharide vaccine (PPSV-23), the presence of SAD, and its association with clinical and laboratory findings in Ataxia-telangiectasia (A-T) and selective immunoglobulin A deficiency (SIgAD) patients.

METHODS

32 A-T patients and 43 SIgAD patients were included in the study. Samples of the patients were obtained before and three weeks after vaccination with PPSV-23. Specific immunoglobulin G (IgG) directed towards pneumococcal capsular antigen and specific antibodies against whole pneumococcal antigens was measured.

RESULTS

Comparison of the response to vaccination revealed that 81.3% of A-T patients and 18.6% of the SIgAD patients had an inadequate response to PPSV-23 (p<0.001). The prevalence of recurrent infection (p=0.034) and pneumonia (p=0.003) in SIgAD patients was significantly higher in non-responders than responders. Likewise, the number of marginal zone B cells (p=0.037), transitional B cells (p=0.019), plasmablasts (p=0.019), CD8+ naïve T cells (p=0.036), and percentage of CD8+ T cells (p=0.047), switched memory B cells (SMB) (p=0.026) and immunoglobulin M (IgM) memory B cells (p=0.022) in SIgAD patients were significantly lower in non-responder group than responder group. In contrast, the percentage of CD4 T+ cells in A-T patients was lower in the non-responder group than responders (p=0.035).

CONCLUSION

SAD is more frequent in A-T patients than SIgAD patients. The role of SMB and T cells should not be underestimated in SAD.

Loss of atm in Zebrafish as a Model of Ataxia-Telangiectasia Syndrome

Ataxia-telangiectasia mutated (ATM) is a key DNA damage signaling kinase that is mutated in humans with ataxia-telangiectasia (A-T) syndrome. This syndrome is characterized by neurodegeneration, immune abnormality, cancer predisposition, and premature aging. To better understand the function of ATM in vivo, we engineered a viable zebrafish model with a mutated atm gene. Zebrafish atm loss-of-function mutants show characteristic features of A-T-like motor disturbance, including coordination disorders, immunodeficiency, and tumorigenesis. The immunological disorder of atm homozygote fish is linked to the developmental blockade of hematopoiesis, which occurs at the adulthood stage and results in a decrease in infection defense but, with little effect on wound healing. Malignant neoplasms found in atm mutant fish were mainly nerve sheath tumors and myeloid leukemia, which rarely occur in A-T patients or Atm-/- mice. These results underscore the importance of atm during immune cell development. This zebrafish A-T model opens up a pathway to an improved understanding of the molecular basis of tumorigenesis in A-T and the cellular role of atm.

Atypical Ataxia Presentation in Variant Ataxia Telangiectasia: Iranian Case-Series and Review of the Literature

Ataxia-telangiectasia (AT) is a rare autosomal recessive neurodegenerative multisystem disorder. A minority of AT patients can present late-onset atypical presentations due to unknown mechanisms. The demographic, clinical, immunological and genetic data were collected by direct interview and examining the Iranian AT patients with late-onset manifestations. We also conducted a systematic literature review for reported atypical AT patients. We identified three Iranian AT patients (3/249, 1.2% of total registry) with later age at ataxia onset and slower neurologic progression despite elevated alpha-fetoprotein levels, history of respiratory infections, and immunological features of the syndrome. Of note, all patients developed autoimmunity in which a decrease of naïve T cells and regulatory T cells were observed. The literature searches also summarized data from 73 variant AT patients with atypical presentation indicating biallelic mild mutations mainly lead to an atypical phenotype with an increased risk of cancer. Variant AT patients present with milder phenotype or atypical form of classical symptoms causing under- or mis- diagnosis. Although missense mutations are more frequent, an atypical presentation can be associated with deleterious mutations due to unknown modifying factors.

Childhood-Onset Movement Disorders Can Mask a Primary Immunodeficiency: 6 Cases of Classical Ataxia-Telangiectasia and Variant Forms

Ataxia-telangiectasia (A-T) is a neurodegenerative and primary immunodeficiency disorder (PID) characterized by cerebellar ataxia, oculocutaneous telangiectasia, immunodeficiency, progressive respiratory failure, and an increased risk of malignancies. It demands specialized care tailored to the individual patient’s needs. Besides the classical ataxia-telangiectasia (classical A-T) phenotype, a variant phenotype (variant A-T) exists with partly overlapping but some distinctive disease characteristics. Here we present a case series of 6 patients with classical A-T and variant A-T, which illustrates the phenotypic variability of A-T that can present in childhood with prominent extrapyramidal features, with or without cerebellar ataxia. We report the clinical data, together with a detailed genotype description, immunological analyses, and related expression of the ATM protein. We show that the presence of some residual ATM kinase activity leads to the clinical phenotype variant A-T that differs from the classical A-T. Our data illustrate that the diagnosis of the variant form of A-T can be delayed and difficult, while early recognition of the variant form as well as the classical A-T is a prerequisite for providing a correct prognosis and appropriate rehabilitation and support, including the avoidance of diagnostic X-ray procedures, given the increased risk of malignancies and the higher risk for side effects of subsequent cancer treatment.

Analysis of Clinical and Genetic Characterization of Three Ataxia-Telangiectasia Pedigrees With Novel ATM Gene Mutations

OBJECTIVE

The clinical manifestations of ataxia-telangiectasia (AT) are very complex and are easily misdiagnosed and missed. The purpose of this study was to explore the clinical characteristics and genetic features of five pediatric patients with AT from three pedigrees in china.

METHODS

Retrospectively collected and analyzed the clinical data and genetic testing results of five AT patients diagnosed by the Whole-exome sequencing followed by Sanger sequencing. The five patients with AT were from three pedigrees, including two female patients (case 1 and case 2) in pedigree I, one male patient (case 3) in pedigree II, and two male patients (case 4 and case 5) in pedigree III. According to the United Kingdom Association for Clinical Genomic Science Best Practice Guidelines for Variants Classification in Rare Disease 2020 to grade the genetic variants.

RESULTS

Five patients had mainly clinical presentations including unsteady gait, dysarthria, bulbar conjunctive telangiectasia, cerebellar atrophy, intellectual disability, stunted growth, increase of alpha-fetoprotein in serum, lymphopenia. Notably, one patient with classical AT presented dystonia as the first symptom. One patient had recurrent infections, five patients had serum Immunoglobulin (Ig) A deficiency, and two patients had IgG deficiency. In three pedigrees, we observed five pathogenic variants of the ATM gene, which were c.1339C>T (p.Arg447Ter), c.7141_7151delAATGGAAAAAT (p.Asn2381GlufsTer18), c.437_440delTCAA (p.Leu146GlnfsTer6), c.2482A>T (p.Lys828Ter), and c.5495_5496+2delAAGT (p.Glu1832GlyfsTer4). Moreover, the c.437_440delTCAA, c.2482A>T, and c.5495_5496+2delAAGT were previously unreported variants.

CONCLUSIONS

Pediatric patients with classical AT may present dystonia as the main manifestation, or even a first symptom, besides typical cerebellar ataxia, bulbar conjunctive telangiectasia, etc. Crucially, we also found three novel pathogenic ATM gene variants (c.437_440delTCAA, c.2482A>T, and c.5495_5496+2delAAGT), expanding the ATM pathogenic gene mutation spectrum.